A fuel cell is a device that converts a fuel into electricity through an electrochemical reaction. Fuel cells have applicability in a wide range of stationary and portable applications. Fuel cells vary in capacity and size. Some fuel cells are small and portable. Other fuel cell systems are very complicated plants that produce relatively large amounts of electrical power.
Fuel cells need fuel and an oxidant to operate. The fuel cell can run as long as fuel and an oxidant are supplied to the fuel cell. Fuel cells can be designed to operate using a wide range of fuels such as hydrogen, methanol, butane, formic acid, and borohydride compounds. Since fuels is consumed as a fuel cell operates to generate electrical power, a fuel-cell-powered device requires a refueling mechanism. Some fuel-cell-powered devices have refillable fuel cartridges. Other fuel-cell-powered devices have built-in on-board fuel storage reservoirs.